I can see why they would put him in your class. Making friends and talking with native speakers of a language is the best way to learn. It isn't good if he is interrupting your class though. Maybe you can make him students leads in a weekly project where each student 'teaches' English. That way he gets a turn to publicly talk and also pays attention when others are talking. You can also deal with difficult students bu giving them leadership roles. When you're talking, you can ask him to jot down your 'instructions' on the board.
A good thing to do whenever a new student joins is to take a class off to establish ground rules. It can be a class activity where the students suggest what the rules should be and what the penalty for not following it is. The rules have to be such that even you, as a teacher, follow it. So if one of the rules is punctuality and you are late, you will have to undertake the penalty. Penalties are usually silly things like - sing a song, tell a joke, do a spot dance etc. And when the students suggest these rules, they are more likely to follow it.